Australian Open, Day 10: Serena upset, Federer slides past Tsonga

There are few times that an entire country can appreciate how big an upset in a Grand Slam event really is. We've seen big names go down because of injury before, but to see a young American in Sloane Stephens take out the biggest name in the women's game (and one of two sisters that brought women's tennis back to the United States) is pretty remarkable.

What Stephens did on Wednesday night shouldn't be soon forgotten. Sure, she had Williams on the ropes because of injury, and catching her at such a vulnerable point is pretty lucky for the 19-year-old, but it wasn't like Williams was planning on retiring at any point in the match (The best example of this came when Stephens was serving for the second set up 5-4 and after going up 30-0 had to watch Williams repeatedly bang winners off Stephens' second serve, showing that while she might not have a ton of mobility at that very moment, she could still sting a forehand).

It wasn't a win with an asterisk for Stephens. She beat Williams in the quarterfinals of a tournament that has seen Serena leave as the champion five different times. The win was important for the American youth, who haven't showed a ton of promise in years and could use a face to lift the game of tennis back up to where it was over a decade ago. Sloane is definitely the underdog in her next match, but what she did was impressive and no injury to her opponent should take away from that.

Federer survives the Tsonga scare -- There are few opponents that Roger Federerprobably isn't excited to see before making it to a Grand Slam semifinals, but Jo-Wilfried Tsonga is one of them.

Tsonga, who upset Federer in 2011 Wimbledon quarterfinals, might have dropped the first set tiebreaker, but a bounce back win in the second set and a match-saving win in the fourth forced this match to, like that Wimbledon upset, go five sets.

Before Wednesday, Federer had yet to drop a single set in Australia (he hadn't even been broken until Tsonga got him late in the first set), but the great champion found an extra gear in the last set and was able to overcome Tsonga.

The best news of all this? Federer goes up against Andy Murray in an incredibly exciting semifinals, with the winner most likely going on to play Novak Djokovic, who plays David Ferrer on Thursday for a spot in the finals.